中文摘要：

以正硅酸乙酯（TEOS）为前驱物，无水乙醇为共溶剂，盐酸为催化剂，双十八烷基二甲基氯化铵（DODAC）为添加剂制备阳离子杂化硅溶胶。通过分析溶胶在胶凝之前相关性能的变化，探讨了氯化钠浓度对阳离子杂化硅溶胶凝胶化的作用机理。结果表明氯化钠可以使溶胶体系粘度增大、透光率减小、Zeta电位降低、凝胶化时间缩短。说明氯化钠能使硅溶胶颗粒表面的离子头之间的排斥作用减弱，溶胶颗粒脱离水相的趋势增大，促进了颗粒之间的聚集，虽然氯化钠还能使体系的pH值降低，凝胶速度减慢，但促凝作用比缓凝作用更显著，并且浓度越大促凝作用越强。

英文摘要：

Cationic silica sols were prepared by sol-gel method with tetraethoxysilane as precursor, ethanol as solvent, dilute hydrochloric as catalyst and dioctadecyl dimethyl ammonium chloride as additive. By analyzing the correlation property of the cationic silica before its gelation, the action mechanism of sodium chloride was discussed in the gelation of the cationic silica sols. The data show that the sodium chloride can increase the viscosity, reduce the transmittance and the zeta potential and shorten gelation time, which main because it can decrease the repulsion between the cationic and increase the tendency that the cationic escape from the water, which promoted the accumulation of particles. The sodium chloride decreases the pH value of the system and the rate of gelation, but the procoagulant effect is stronger than the retarding effect and the proeoagulant effect is enhanced with the increase of the sodium chloride concentration.